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Do I just need to add a 10 kΩ resistor on one of the GPIO pins of my ESP32 in order to use it to connect to the TCA9548A (Adafruit EMC2101) reset pin?

The RST pin on the TCA9548A (Adafruit EMC2101) needs to be pulled low (gnd) in order to restart the TCA9548A (Adafruit EMC2101). Since the ESP32 has the GPIO at 3.3 V would hooking a 10 kΩ resistor bring that down to the level of gnd?

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But I also already see that the module already has a 10 kΩ resistor connected to the RST pin on the TCA9548A (Adafruit EMC2101):

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So do I just need to connect the GPIO to the RST pin without adding my own 10 kΩ resistor?

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  • \$\begingroup\$ The Adafruit EMC2101is a fan controller (which does not appear to break out a reset pin) and I see no mention of a TCA9548A on the data sheet. Http://adafruit.com/product/4808 . Have you mentioned EMC2101 simply as an example device connected to the I2C multiplexer TCA9548A because it doesn't really seem relevant to your question. \$\endgroup\$
    – 6v6gt
    Commented Jul 14 at 2:34

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So long as the grounds are common you only need to tie the GPIO to the adafruit reset pin. A pull up resistor is already provided for you, so you don’t need one. Your IO can be driven high or into high impedance (input mode) to keep the adafruit out of reset. Drive the pin low to force a reset.

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  • \$\begingroup\$ Wouldn't connecting the RST pin to a ESP32 GPIO pin make it loop reset over and over again? Is it not LOW on any GPIO pin until you turn it on? \$\endgroup\$
    – StealthRT
    Commented Jul 15 at 2:18
  • \$\begingroup\$ it would reset/stall slightly on boot, no big whoop. \$\endgroup\$
    – dandavis
    Commented Jul 16 at 9:56
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    \$\begingroup\$ No, the ESP32 pins (like most if not all processors) are in input mode on startup. The pins will only be driven low once you configure them to outputs and drive them low. \$\endgroup\$
    – EricEverton
    Commented Jul 16 at 15:36

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